Gas tube



Oct. 7, 1941. 1 R. H. BADGLEY 2,258,437

GAS TUBE Filed Aug. 29, 1940 /N l/E N TOR F/G.4 i TTORNEY Patented Oct. 7, 1941 ENT OFFICE GAS TUBE Robert H. Badgley, Morris Plains, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application August 29, 1940, Serial No. 354,681

4 Claims.

This invention relates to circuit makers and breakers and particularly to that type known as triggertubes wherein an inert gas surrounding a pair of electrodes is caused to ionize and thereby become a conducting path between said electrodes. r

The object of the invention is to provide for selective response to some external critical stimulus. Accordingly the tube of the present invention is provided with a pair of electrodes one of which is comparatively long With a free end so spaced in relation to the other of said electrodes that the breakdown potential of the tube is not reached until the free end moves closer to the other electrode. A feature of the invention is a movable electrodeby means of which the gap is shortened so that by mechanical movement the tube is fired.

Another feature of this invention is the use of a tuned reed as .one electrode of, a trigger tube. It is an inherent characteristic of various bodies such as reeds or tuning forks, to respond at comparatively large mechanical amplitude to a driving force if it corresponds to the natural frequency of the body. For other frequencies, the response is small.

In an inert gas-filled tube, the potential necessary to cause ionization of the gas vares with the distance between the electrodes. If the correct gas is used, it is only necessary 'to increase the separation of the electrodes a small amount in order to cause a large increase in the ionization potentialof the gap and by the same token it requires only a slight decrease in the separation of the electrodes to reachthe ionization potential. Accordingly, the mechanical response of the tuned reed to a small external stimulus is` sufiicient tofire the tube. Such a device is sharply tuned to a particular frequency.

In accordance with another feature of the invention a combination frequency device is pro- Vided by placing a plurality of gaps in series each Controlled by a tuned reed of a different frequency. Such a tube can only be fired by simultaneously stimulating all of its reeds and hence a relay means of a highly selective nature is provided.

Another feature of the invention is a band-pass device in which a plurality of reeds of closely grouped frequency response are connected in parallel whereby the device will respond to a frequency within a band. This device therefore has a broad response and may be used where a sharply tuned device would be disadvantageous.

In accordance with another feature of the invention this device may be used to relay interrupted or alternating current by applying an interrupted or alternating potential to its electrodes.'

In accordance with a further feature the external stimulus for causing the resonant vibration of the reed may be supplied by an alternating potential applied to the electrodes which may be in the form of parallel surfaces whereby an electrostatic 'force between the two is set up and results in the building up of mechanical resonance.

In accordance with another feature of the invention and which forms the specific feature of my copending application Serial No. 354,682, filed on even date herewith other external stimuli may :be used to cause mechanical movement of one electrode. In particular an electrode may be provided in the form of a bimetallic strip responsive to temperature changes.

The drawings consist of a single sheet having four figures.

Fig. 1 is a cross-sectional view of a gas tube having a single gap;

Fig. 2 isa cross-sectional view of a gas tube having vthree gaps in series;

Fig. 3 is a cross-sectional view of a gas tube having five gaps in multiple and Fig. 4 Vis a perspective View of the two elements forming the electrode assemblies used in the device of Fig. 3.

In Fig. 1 a glass envelope encloses an electrode assembly which is surrounded or immersed in an inert gas. Two terminals 2 and 3 connect to the electrodes. One electrode 4 is comparatively long and secured at one end so that the other end is free to vibrate; This electrode is made of magnetic material` and has a natural period of vibration which may be adjusted in any well-known manner. Another electrode 5 is short and stationary. Both of these electrodes are mounted upon a piece of insulating material 6 in any convenient and well-known manner. A coil 1, external to the envelope, may be energized by an alternating current whose frequency will set the movable electrode 4 into vibration. The power required for moving the electrode 4 is insignificant due to the resonance effect, since it requires very little energy to set a reed into Vibration at its own natural period of vibration.

The terminals 2 and 3 are connected into a circuit arrangement whereby a potential is established across the tube insufficient to cause the tube to break down while the reed 4 is stationary. However, when the reed 4 is set into vibration its end approaches the other electrode 5 and through this reduction in the gap the tube is caused to break down and current to flow from the terminal 2 to the terminal 3.

In Fig. 2 another type of tube is shown. Here the envelope |4 covers an electrode assembly comprising three movable electrodes 8, 9 and IO and three corresponding stationary electrodes ll, 12 and |3. The two outside terminals |5 and 16 are connected to the movable electrode 8 and the stationary electrode |3, respectively. When the external coil |1 is energized by composite current containing the frequencies for causing the three different movable reeds 8, 9 and H] to vibrate, the tube will break down and a current will flow in series from terminal |5 through reed 8, stationary electrode II, reed 9, stationary electrode |2, reed IO, stationary electrode |3 and terminal IB. The spacer I 8 and the spacer 19 are of conducting material, so that stationary electrode Il is connected to reed 9 and stationary electrode |2 is connected to reed IO. The base 20 is formed of insulating material and the spacers, such as 2|, 22, 23 and 24, are also formed of insulating material;

If the coil |1 is energized with alternating current, which will cause only one reed, for instance reed 9, to vibrate, the tube will not break down. It is only when the energization of the coil |1 causes all three movable reeds to Vibrate at the same time that the desired effect is achieved.

In Fig. 3 an envelope 25 encloses a reed and stationary terminal assembly whereby a plurality of reeds differing very slightly in their natural periods of vibration are mounted in multiple so that when the external coil 26 is energized by any one of a number of frequencies closely associated with each other the tube will break down. Two hexagonal metal or conducting pieces 21 and 28 are provided and from each of these a conducting terminal 29 or 30 is used for making connection to an external circuit. Upon the hexagonal piece 21 are mounted five reeds 3|, 32, 33, 34 and 35. Upon the hexagonal piece 28 are mounted five stationary terminals 36, 31, 38, 39 and 48. The two hexagonal pieces are secured together by an insulating piece 4|.

It may be noted that the hexagonal pieces 21 and 28 are of the same size and that proper gap spacing, for instance between the reed 35 and the corresponding stationary terminal 36, is secured `filled with an inert gas, a structure within said envelope comprising a plurality of tuned magnetic reeds each having a different natural period of vibration, a companion electrode adiacent each of said tuned reeds, said reeds each being mounted with one end thereof secured and the other end thereof free to vibrate, said electrodes each being mounted to form a normal gap with its companion reed transiently diminishable during the vibration of said companion reed, a pair of terminals connected to said structure and sealed through said envelope, and a coil surrounding said envelope for producing a magnetomotive force in the direction of the axis of said tubular envelope for setting said reeds into vibration.

3. A relay comprising a sealed tubular envelope filled with an inert gas, a structure within said envelope comprising a plurality of tuned magnetic reeds 'each having a different natural period of vibration, a companion electrode adjacent each of said tuned reeds, said reeds each being mounted With one end thereof secured and the other end thereof free to Vibrate, said electrodes each being mounted to form a normal gap with its companion reed transiently diminishable during the vibration of said companion reed, said reeds and said electrodes being connected With said gaps in series, a pair of terminals connected to said structure and sealed through said envelope, and means external to said envelope for setting said reeds into vibration.

4. A relay comprising a sealed tubular envelope filled with an inert gas, a structure within said 'envelope comprising a plurality of tuned magnetic reeds each having a different natural period of vibration, a companion electrode adjacent each of said tuned reeds, said reeds each being mounted with one end thereof secured and the other end thereof free to Vibrate, said electrodes each being mounted to form a normal gap with its companion reed transiently diminishable during the vibration of said companion reed, said reeds and said electrodes being connected with said gaps in multiple, a pair of terminals connected to said structure and sealed through said envelope, and means external to said envelope for setting said reeds into vibration.

ROBERT H. BADGLEY. 

